Shrimp are typically gathered for marketing by means of shrimp trawls which are pulled through the water, typically along the bottom of a body of water by shrimp boats or by other suitable means. After the shrimp are caught they are typically stored in ice or in other conditions of cold storage until they can be transported to a shrimp processing facility. At the shrimp processing facility the shrimp may be packed in a heads-on condition or in a headless condition for transportation to a marketing facility or to the ultimate consumer. The sales price of shrimp is decreased materially by the various handling processes that are employed in grading and subsequently deheading the shrimp or deheading and then grading them for size and quality.
Prior to packing the fresh caught shrimp in ice in the cargo holds of shrimp trawlers, it is desirable to accomplish grading of the shrimp so that they may be sold and shipped without significant further handling. Such on board grading of shrimp is ordinarily not practical since most shrimp grading machines are of such large dimension that they cannot be efficiently mounted on a typical shrimp trawler. Moreover, shrimp grading machines are typically of sufficiently expensive nature that it is impractical to consider locating them on board shrimp trawlers. Although in many cases fresh caught shrimp are graded by manual operations on board shrimp trawlers for the purpose of protecting the catch by immediate cooling with ice to thus enhance the storage life thereof, manual shrimp grading operations can only be conducted if the volume of shrimp being caught is fairly low. In fact it has been determined that only approximately 10% of the shrimp being caught are manually graded and/or deheaded. Further, manual grading operations during shrimp catching and on board processing activities significantly enhances the cost of the shrimp that these activities are generally considered impractical. It is considered desirable therefore to place on board shrimp trawlers and other such vessels a shrimp grading machine of sufficiently small dimension and of sufficiently low cost as to be commercially acceptable for most shrimp trawlers.